ngrok is a reverse proxy that creates a secure tunnel between from a public endpoint to a locally running web service. ngrok captures and analyzes all traffic over the tunnel for later inspection and replay.

• Expose any http service behind a NAT or firewall to the internet on a subdomain of ngrok.com
• Expose any tcp service behind a NAT or firewall to the internet on a random port of ngrok.com
• Inspect all http requests/resposes that are transmitted over the tunnel
• Replay any request that was transmitted over the tunnel

• Temporarily sharing a website that is only running on your development machine
• Demoing an app at a hackathon without deploying
• Developing any services which consume webhooks (HTTP callbacks) by allowing you to replay those requests
• Debugging and understanding any web service by inspecting the HTTP traffic
• Running networked services on machines that are firewalled off from the internet

ngrok has no runtime dependencies. Just download a single binary for your platform and run it. Some premium features are only available by creating an account on ngrok.com. If you need them, create an account on ngrok.com.

• Linux
• Mac OSX
• Windows

ngrok developer's guide